The use and abuse of antibiotics in elective colorectal surgery: The Saga Continues…

"A breach in the protocol for no good reason": a surgical antimicrobial prophylaxis experience in an Ethiopian academic medical center

BACKGROUND

An appropriately administered surgical antimicrobial prophylaxis decreases the rate of surgical site infections. Although evidence-based clinical practice guidelines have been published on surgical antimicrobial prophylaxis, the rate of adherence to the protocol and the impact of extending antimicrobial prophylaxis postoperatively is yet to be well elucidated.

METHOD

A total of general surgery and vascular surgery patients with clean and clean contaminated wound undergoing elective surgical procedures were included in the study. The rate of surgical antimicrobial prophylaxis utilization, the proportion of patients whom had their antimicrobial prophylaxis extended beyond 24 h and the rate of surgical site infections across groups were evaluated.

RESULTS

The surgical antimicrobial prophylaxis utilization rate was 90.5%. Of these patients, 12.6% were unnecessarily administered with antibiotics. An "extended" antibiotics administration beyond 24 h after the surgery was found in 40.2%. Gastrointestinal and hepato-pancreatico-biliary surgery patients had 7.9-fold rate of "extended" surgical antimicrobial prophylaxis beyond 24 h, AOR 7.89 (95% CI 3.88-20.715.62, p value < 0.0001). The overall rate of surgical site infection was 15(6.8%). The "extended" regimen of prophylactic antibiotics had no effect on the rate of surgical site infections.

CONCLUSION

Less than half of the patients included here had surgical antimicrobial prophylaxis regimen in accordance with the existing guidelines. The most common protocol violation was noted as extension of antimicrobial prophylaxis for more than 24 h after surgery. The extension of antimicrobial prophylaxis did not decrease the rate of surgical site infections, reaffirming the evidence that prophylactic extension of surgical antimicrobial prophylaxis is unnecessary.

Metronidazole affects breast cancer cell lines

PURPOSE

The aim of our study was to evaluate the impact of metronidazole (MTZ) on cytotoxicity and DNA synthesis in MCF-7 (estrogen receptor positive) and MDA-MB-231 (estrogen receptor negative) breast cancer cell lines.

MATERIAL/METHODS

Toxicity of MTZ was determined by MTT test. MCF-7 and MDA-MB-231 cells were incubated with metronidazole used in different concentrations for 24, 48 and 72 hours. The effect of MTZ on DNA synthesis was measured as [3H]-thymidine incorporation.

RESULTS

We showed that MTZ in concentration 250 μg/ml significantly increases the growth of MCF-7 cell lines after 24 hours of incubation, but it reduces cell viability in concentrations 1 and 10 μg/ml 72 hours after the drug application. Significant increase of MDA-MB-231 cell viability was obtained in MTZ concentration of 250 μg/ml after 24 and 72 hours. The increase of [3H]-thymidine incorporation in MCF-7 cell line treated with MTZ in concentration 250 μg/ml was statistically significant after 24 hours. Great suppression of cell proliferation was obtained in MDA-MB-231 breast cell line after application of the following concentrations of MTZ: 0.1 μg/ml (after 24 hours) and 0.1, 10, 50, 250 μg/ml (after 72h).

CONCLUSIONS

We found that metronidazole exerts different dose- and time- dependent effects on human breast cancer cell lines characterized by presence or absence of estrogen receptors. We suggest that these discrepancies may be influenced by the estrogen signaling.

Cefotetan versus conventional triple antibiotic prophylaxis in elective colorectal cancer surgery

This study examined infectious outcomes in elective colorectal cancer surgery between cefotetan alone or conventional triple antibiotics. From January to December 2007, 461 consecutive primary colorectal cancer patients underwent elective surgery. Group A contained 225 patients who received conventional triple antibiotics (cephalosporin, aminoglycoside and metronidazole) for prophylaxis, and group B contained 236 patients who received cefotetan alone for prophylaxis. Treatment failure was defined as the presence of postoperative infection including surgical-site infection (SSI), anastomotic leakage, and pneumonia or urinary tract infection. The two groups were similar in terms of demographics, American Society of Anesthesiologists (ASA) score, tumour location, stage, surgical approach (conventional open vs. laparoscopy-assisted), and type of operation. The treatment failure rates were 3.1% in Group A and 3.4% in Group B (absolute difference, -0.3%; 95% confidence interval [CI], 0.39 to 3.07, P=0.866), with SSI being the most common reason for failure in both groups (2.7% in Group A and 3.0% in Group B [absolute difference, -0.3%; 95% CI, 0.37 to 3.37, P=0.846]). Cefotetan alone is as effective as triple antibiotics for prophylaxis in primary colorectal cancer patients undergoing elective surgery.

Increased incidence of postoperative infections during prophylaxis with cephalothin compared to doxycycline in intestinal surgery

Background

The antibiotics used for prophylaxis during surgery may influence the rate of surgical site infections. Tetracyclines are attractive having a long half-life and few side effects when used in a single dose regimen. We studied the rate of surgical site infections during changing regimens of antibiotic prophylaxis in medium and major size surgery.

Methods

Prospective registration of surgical site infection following intestinal resections and hysterectomies was performed. Possible confounding procedure and patient related factors were registered. The study included 1541 procedures and 1489 controls. The registration included time periods when the regimen was changed from doxycycline to cephalothin and back again.

Results

The SSI in the colorectal department increased from 19% to 30% (p = 0.002) when doxycycline was substituted with cephalothin and decreased to 17% when we changed back to doxycycline (p = 0.005). In the gynaecology department the surgical site infection rate did not increase significantly. Subgroup analysis showed major changes in infections in rectal resections from 20% to 35% (p = 0.02) and back to 12% (p = 0.003).

Conclusion

Doxycycline combined with metronidazole, is an attractive candidate for antibiotic prophylaxis in medium and major size intestinal surgery.